1. Field of the Invention
This invention relates to a fugitive ink composition for marking fibrous material, and a process of providing a fugitive mark on fibrous material.
2. Description of the Prior Art
Cotton is usually picked by a mechanical harvester which is driven along the row of cotton plants. The harvested cotton is collected in a large bin on the harvester. When the bin is filled, the seed cotton may be compressed into a module formed on a pallet, according to the method disclosed in U.S. Pat. No. 3,749,003, the content of which is hereby incorporated by reference. The module-supporting pallets are transported to the gin mill after harvesting where they are stored in an open gin yard.
Since the cotton harvested by numerous farmers may be temporarily stored at a single gin yard, farmers have sought a method of marking their modules for identification purposes. Gin operators also wish to identify modules for a number of reasons, including the date of delivery and quality. The conventional method of marking modules is the application of paint, especially crosslinked acrylic polymer spray paints. However, the paint mark survives the mechanical processing of the gin and mars the appearance of the cotton. Further, the paint mark is not fully eradicated upon the bleaching and scouring processes necessary to produce pure white cotton fabric. Thus, textile mills often declined to accept cotton tainted with paint contamination.
Various attempts have been made to mark cotton modules with compositions, described as being "fugitive". Fugitive is used here to describe a colored composition that is substantially removed by the subsequent processing of the substrate to which it is applied so that the appearance of the final product is not marred. However, the problem with known fugitive compositions is that some, such as cationic dyes, are bleached out in sunlight while others are not fully decolorized by the subsequent processing of the marked cotton.
As can be understood, the art is replete with compositions used as marking materials. However, each possesses disadvantages which detract from its ability to be used as a fugitive ink composition. For example, U.S. Pat. No. 499,161 describes a process for printing on cotton utilizing colors fixed by a metallic tannate. However, the use of a metallic tannate as a mordant dye permanently fixes the dyestuff upon the cotton.
U.S. Pat. No. 1,050,236 discloses a printing ink that includes a metallic salt and tannic acid. Again, as this ink is suitable for typewriter ribbons, it cannot be considered a fugitive composition.
U.S. Pat. Nos. 4,167,510 and 4,170,669 exemplify conventional fugitive tints used in identifying textiles during processing. These tints are pastel, are removed by water, and are thus not suitable for providing dark identification marks on fibrous material that is exposed to rain.